A few years ago, scientists began worrying that blue catfish, the much larger cousins of those squirmy, yellowish bottom feeders, might take over in Chesapeake Bay. They’re big—better than 100 pounds in some cases--voracious eaters and they’re prolific. So, at least one seafood wholesaler appropriated a slogan applied to other invasive fish--eat ‘em to beat ‘em—and began aggressively marketing them. And local watermen have found a new market and seemingly endless supply.

There is, for example, Jamie Bowling, a Charles County, Maryland, waterman, who set out on the Potomac one recent morning as a waning gibbous moon hung silver in a cobalt sky.

He and his son, Sam, left the dock at a local boat ramp, heading for their trotline, stretching for maybe 500 feet near the mouth of Gunston Cove on the Virginia side of the river. It’s marked at either end with green floats and interspersed with empty one gallon plastic jugs.

Bowling says he thinks he’s doing something good for the environment by catching them.

"Crabbing had gotten to be very poor," he said. "And I just felt like when I was catching these blue cats I was benefiting the environment and I was giving the crabs a little break."

The fish, native to the Mississippi, Ohio and Missouri river basins, were introduced to the James, Rappahannock and York rivers in Virginia in the 1970s and 80s as a game fish.

The rationale, says Troy Tuckey, a researcher at the Virginia Institute of Marine Science, was they "grow pretty big, they’re fun to catch, hook and line," and regulators said, "eh, you know, we did this in other locations, let’s try it here in Virginia."

Since then, however, scientists have grown "concerned" about the growing populations of blue catfish, he said.

"Blue catfish eat everything, including each other, and there aren’t a whole lot of things that eat them once they get a certain size."

The fish can grow up to four and a half feet in length and weigh well more than 100 pounds. And they "really, really, really like Chesapeake Bay tributaries," he says.

In fact, blue catfish are more abundant in the Chesapeake tributaries than in their native waters or "other areas they’ve been introduced," Tuckey said.

He says fisheries scientists figured blue catfish are a fresh water species; the saltier water close to the mouths of the rivers would keep them from wandering. But they were wrong. The fish have spread north into the Potomac and other Maryland rivers.

Mary Groves, who studies blue catfish for Maryland’s Department of Natural Resources, says they’ve shown up in the Patuxent, the Upper Bay and Eastern Shore rivers, which suggests to her people have been catching them and moving them around.

It wouldn’t make sense, she says, that those fish would swim to rivers that far away. And besides, “there have been people that have complained that they saw somebody dumping fish into the river.”

It’s not unusual that people move fish to stock their own waterways, she says.

So, Maryland fisheries regulators have developed the attitude, "if you can take it out, eat it, fine, please do that," she said. They want to come up with a plan to "keep the numbers to the point of where it’s manageable" because "like most of your invasive species you’re not going to get rid of them."

And that’s where Tim Sughrue comes in.

He’s a fisheries scientist and vice president of Congressional Seafood, located in a sprawling warehouse off U.S. 1 just south of Baltimore. They process as much as 40,000 pounds of fish on a Friday alone. And some 8,000 pounds of that is blue catfish, headed for restaurants like Clyde’s of Georgetown and grocery chains like Whole Foods and Wegmans.

He calls the blue catfish invasion "a real time environmental catastrophe happening in the Chesapeake Bay right under our noses" that threatens to "100 percent change the dynamic in the Chesapeake over the next two decades."

And the only way to stop it is to "create a market for this fish which happens to taste fantastic and look fantastic in a retail setting."

Other fisheries scientists don’t see it in quite so apocalyptic terms. Matt Ogburn, an ecologist at the Smithsonian Environmental Research Center who’s been studying blue catfish, says there’s been "concern" about the fish because they "reproduce quite a lot."

"Their abundance can be very high in the James and Potomac rivers, especially," he said. "And they eat a wide variety of things, but especially they eat fish as they get bigger."

He says they were one of the last species introduced to Chesapeake tributaries before scientists understood that introducing non-native species can have negative effects.

Of course, Martin Gary, executive director of the Potomac River Fisheries Commission, says not all those effects have been negative. There’s the effect on local watermen, for example. They caught more than a million pounds of blue catfish in the Potomac alone last year and are on track to easily surpass that this year.

Part of those growing catch figures are "a function of the number of people that are going to fish for blue catfish," he said. "It’s become lucrative; it’s become a win, win, win all around."

It’s not that he likes having a top of the line predator predator in his river, but they’re good to eat, they’re safe to eat—up until they’re about three feet long they’re relatively free of the mercury and PCBs that often accumulate in fish—and watermen have become pretty efficient at catching them.

By the time Jamie and Sam Bowling reach their trotline there’s a slash of orange on the eastern horizon. As they set up Jamie chops up a bucket of eels for bait and Sam brings the green float across the blunt bow of their 21-foot Carolina skiff. They work, hardly speaking to each other.

Jamie, on starboard, hauls in the line, pulling one blue catfish after another out of the water. He springs the hook and drops the fish into the bottom of the boat. Sam rebaits the hook and leads the line back into the water. The fish, at least three feet long, blue on top, with white bellies, flop around. They make a noise almost like barking with their swim bladders.

At the end of the first pass, Jamie turns the boat around and heads back to the beginning of the line while Sam tosses the fish into 35-gallon ice chests.

They’ll make three more passes over the next four hours, filling six of those ice chests with barking blue catfish and leaving nearly a dozen more flopping in the bottom of the boat. And in all that time, they only catch two fish that aren’t blue cats—one gar that didn’t survive on the hook and one that looked like a cross between a blue and a channel catfish.

After the last pass, they head back to the dock to haul the boat out of the water to meet one of Tim Sughrue’s trucks. They’ll be back the next day and the next, making a living and, as Bowling puts it, doing something good for the environment.

The Chesapeake: A Journalism Collaborative is funded by the participating stations with grant support from the Clayton Baker Trust, The Bancroft Foundation, Michael and Ann Hankin, The Jim and Patty Rouse Foundation, The Rob and Elizabeth Tyler Foundation, and the Mid-Shore Community Foundation.